Method of making liquid filled golf ball cores



Oct.- 3, 1950 E. C. UHLIG 2,524,587

METHOD ov MAKING LIQUID FILLD GOLF BALI. coREs l Filed May l, 1948 3 Sheets-Sheet 1 0t 3, 1950 E. c. UHLIG 2,524,687

METHOD DF MAKING LIQUID FILLED GDLF BALL coREs Filed May 1, 194s y s sheets-sheet 2 ATTORNE Y oct. 3, 195o E. c. UHU@ '2,524,687

METHOD 0F MAKING LIQUID FILLED GOLF BALL CORES Filed May 1,r 1948 s sheets-sheet s L Jj;

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MIK/4 Ymu www A .TTRNEI Patented Oct. 3, 1950 METHOD OF Ii/IAKING LIQUID FILLED GOLF BALL CORES Edwin C. Uhlig, Greenwood, R. I., assigner to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application May 1, 1948, Serial No. 24,567

4 Claims. (Cl. 18-59) l This invention relates primarily to a novel method of making liquid filled golf ball cores, but it may be employed to make medical bulbs, syringes and other hollow accurately shaped rubber articles.

Liquid sued golf bali cores comprising a 'rubber golf ball core is subjected to a strong compressing force at all times within the golf ball due to the contracting action of the rubber thread wound tightly upon the core to build up the golf ball body.

Liquid lled golf ball cores having a rubber shell have been made heretofore by several diiferent methods. One vis to form semi-spherical shells of vulcanizable rubber and then bring these shells together in a bath of water or other liquids, but it is difficultv to secure a suiiciently strong bond between the semi-spherical shells by this method to prevent the liquids from escaping. It has also been proposed heretofore to produce semi-spherical shells of vulcanizable rubber and then bring them together to form a spherical shell, and ll the same by introducing the liquid through a small tube, but this method is expensive.

The present invention contemplates a simple, practical and inexpensive method of making golf ball cores and other liquid filled shells so that they are accurate as to size andweight and contain the liquid without leakage. One 'important feature of the present invention resides in the method whereby air is excluded from the lled cores, another important feature resides in the method whereby a dozen or more golf ball cores are produced simultaneously, to thereby reduce the cost of manufacture.

If the weight of the golf ball cores is to be `controlled accurately it is necessary to control closely the thickness of the walls of the liquid filled cores and the amount of contained liquid. This Ais because the specific gravity of the rubber used is usually considerably diiierent from that of the contained liquid, for instance, when the liquid used is water, the specific gravity of therubber is about twice that of water as the rubber is weighted with a heavy ller. ITherefore any subin a core will change its weight. The present method permits an accurate control ofthe thickness of the core walls and of the amount of thev conned liquid.

The various features `of the present invention will `be further understood from the following description whenl read in connection with the accompanying drawings which illustrate the steps employed in carrying out the present method, and one practical form of apparatus that may be used in carrying out the method.

In the drawings,

Fig. l is a perspective view, of two rolls of sheet material and a press having plates for uniting the two sheets;

Fig. 2 on a larger scale is a sectional View through the` sheets and a die plate shown in Fig.

Fig. 3 is a perspective view of an envelope or pillow formed by the uniting operation of Fig. 2;

Fig. 4 is a perspective view of apparatus for supporting the envelope of Fig. 3 in a vertical position, and shows means for introducing a measured quantity of liquid into the envelope;

Fig; 5 is a view similar to Fig. 4 showing how the liquid is forced to rise in the envelope to drive out any air the envelope may contain;

Fig. 6 is a sectional view through the envelope after a measured quantity of liquid has been introduced therein and the envelope sealed;

Fig. 7 is a perspective view of a hot water bath in which the envelope of Fig. 6 is heated to soften its walls;

Fig. 8 is a side elevation with parts in section of a press having a pair of mold plates and a cutting die, the press being shown open;

Fig. 9 is anotherview of the press of Fig. 8 taken at right angles to the view of Fig. 8 and shows the upper mold plate moved to an inactive position at the rear of the press, and the lower mold plate raised;l

Fig. 10 is a view of the press taken after the cutting operation of Fig. 9 has been performed and the bottom mold plate has been lowered;

Fig. 1l is a plan view of the bottom mold plate;

Fig. 12 is an enlarged sectional view of two of the golf ball cores shown in Fig. 10;

Fig. 13 is an enlarged sectional view of one of the cores of Fig. 9 showing how the cutter die cuts a liquid iilled core free from its envelope;

Fig. 1 4 is a sectional view through the golf ball core of Fig. 13 after it is removed from the bottom .mold and envelope; and

Fig. 15 isa sectional view through a golf ball core after it has been vulcanized in a, vulcanizing mold and freed of all flashing.

The method of the present invention Was, as above stated, developed primarily to yproduce liquid filled golf ball cores, but may be used to produce other liquid filled shells formed of rubber or other plastic sheet material that will bond one sheet to another under the application of pressure.

The method of the present invention is not limited to the manufacture of spherical molds or shells but can be employed to produce other rounded articles of manufacture such for example as medical bulbs, syringes and other objects having a rounded but non-spherical shape, and after these articles are vulcanized they can be cut at one end to discharge the liquid.

The present method will be described herein in detail as employed in the manufacture of liquid lled golf ball cores but it will be understood that not all of the steps herein described are essential to the present invention. The stock used to produce such cores may be formed of natural or synthetic rubber and may be the same as the rubber stock extensively7 usedr heretofore inthe manufacture of liquid filled golf ball cores.

`In the construction shown in Fig. l ofthe drawings, the spool or roll I supplies the upper sheet I I of: vulcanizable rubber, and the lower spool or 'roll I2 supplies the lower sheet i3 of vulcanizable rubber. Raw or unvulcanized rubber is very tacky so that if the sheets Il and I3 come together they may be hard to separate. The upper face of the sheet I3Vis therefore dusted with an anti-tack substance I4 such as confectionary sugar, and if desired the adjacent face of the sheet II may be similarly dusted. The anti-tack material is preferably soluble in water. The sheets I I and I3 are drawn from their supply rolls to the cutting and marginal edge sealing press shown in Fig. l and which consists of the lower non-moving base I5 upon which is mounted the bottom plate I5', and the upper vertically moving head I6 which has attached to its lower face the upper pressing plate I'I. The desired reciprocating movement may be imparted to the 'head I6 by a link I8 pivotally secured to this head and operatively connected to a rotating disk If the sheets II and I3 of unvulcanized rubber are cut accurately to the desired width before they are wound on the r-olls I0 and l2 the press shown in Fig. l and Fig. 2 need not be provided with trimming cutters at its opposite end to trim the side edges of the sheets, since it will be sufficient to provide the upper plate II with the cutter 2i! positioned as shown in Fig. 2 to eut these sheets I l and I3 after they have been drawn into the press of Fig. 2 just far enough to be completely covered by the upper plate I'I. When 4this press is closed as shown in Fig. 2 a peripheral rib 2! upon the plate I'I'will exert a sealing pressure upon the marginal edges of the sheets entirely around their periphery, except for a small area such as indicated by 22 in Fig. 3. This View of Fig. 3 shows the envelope or pillow 23 after it has been removed from the press of Fig. 2. The reason the sheets II and I3 are not pressed together at 22 is to permit the envelope to be opened at this point to receive a measured quantity of liquid. The pressure exerted by the ribs 2I is suflicient to bond the sheets firmly together through the anti-tack dust I4.

It is very important that after the liquid is introduced in the envelope 23 of Fig. 3 that this envelope be sealed so that it does not contain air, because even if a small amount of air is trapped Within the envelope it will nd its way into the shell cavities with the result that one or more of the golf ball cores produced by this method will be partly filled with air and therefore will not have the proper weight. The liquid used is preferably water which has been boiled to free it from contained air, but other liquids may be used which are not injurious to the rubber shell and do not possess strong anti-tack properties that would prevent the stock from knitting together during the bonding action.

One simple and practical means for introducing in the envelope a measured quantity of liquid, and then sealing the envelope so that it does not contain air is illustrated in Fig. 4 and Fig. 5 wherein there is shown a supporting frame coinprising the base plate 24 and upright plate 25 that is secured rigidly to the base plate. This upright plate 25 is provided with the envelope supporting ribs 26 adapted to support the envelope 23 in a vertical position so that its entrance 22 is at the uppermost portion of envelope. The desired amount of liquid, such for example as boiled water, is introduced into the envelope by means of the flexible tube 2'! that preferably has a stiff lower end that can be easily inserted within the opening 22 of the envelope between the layers II and I3. A The upper end of this tube 2l is connected to a measuring glass or tube 28 which is supported by the upright 25 and is filled to a desired height with liquid. Then after the envelope is positioned as shown in Fig. 4 with the tube 2l inserted in the envelope opening, the valve 29 is turned to thereby permit the measured quantity of liquid within the glass to flow into the envelope 23. After the measuring tube 28 is thus emptied the valve is closed and the tube 2T is removed from the envelope openingr as shown in Fig. 5. The water used is boiled to remove the small Aamount of air which Water usually contains.

It will be apparent that although the envelope 23 contains the desired accurately measured quantity of liquid, it may also contain some undesired air. This air is readily expelled by squeezing the side walls of the envelope 23 to cause the liquid to rise therein to the top of the envelope. The apparatus shown in Figs. 4 and 5 is therefore provided with the envelope pressing plate or board 30 that is hinged to the upright 25 and may be pressed manually against the envelope until it has forced the liquid to the top of the envelope as shown in Fig. 5. Care should be taken not to force any of the liquid out of the envelope. While the parts remain as just described and as shown in Fig. 5 with all of the air forced out of the envelope, the envelope is sealed by exerting a sealing pressure across the filling opening 22. This pressure is conveniently exerted by providing the sealing bar 3l which is pivotally secured to the upright 25 at 32. This pivoted bar is pressed by hand against the portion 22 of the envelope with sufcient force to tightly seal this opening, so as to cause this envelope to retain the desired measured quantity of liquid but no air.

The liquid containing envelope 23 when removed from the apparatus of Fig. 5 will contain a measured amount of water W and will have the appearance in cross-section shown in Fig. 6. It is desirable in accordance with the next step of the present method to heat the envelope of Fig. 6 so as to render the vulcanizable rubber of which it is formed softer and more plastic. This may be accomplished by placing the envelope for a few minutes in the hot water tank 33 having the water inlet pipe 34 and outlet pipe 35 for controlling the temperature and supply of water. The Water in this tank is preferably maintained at a temperature of aboutl35 F. and the envelope may remain thereinfrom about 11/2 to 10 minutes. v

As soon as the envelope 23 is removed from the hot water bath in Fig. 7 itis placed in the press as shown in Fig. 8 to' be subjected to a gradual pressure upon its opposite faces. This press has the side frame 36 and 3l and horizontally extending top rails 38. This frame is provided with the lower mold'plate 39 and upper mold plate 4l). The lower "mold plate 39 is supported and operated by a sliding plunger 4l of a hydraulic ram, not shown, but which has the plunger guiding sleeve ll2. The upper mold plate 4D is provided at its opposite edges with the rollers i3 which roll along the horizontally extending rails 44. The arrangement is such that the mold plate 46 may be moved to an operative position directly above the lower mold plate 39 as shown in Fig. 8, or it can be pushed rearward- 1y to the inoperative position in which it is shown in Fig. 9. I'his lateral movement of the upper mold plate A9 is desirable so that the lower plate 39 may be raised high enough to bring its face into engagement with a-cutting die 55 as shown in Fig. 9, This die is rigidly supported by a block l secured to the rails 38. The lower mold plate 39 has formed in its upper face a` number of approximately semi-spherical mold `cavities 45, and the upper mold plate 40 is provided with a similar set of cavities lll. Th number of these cavities may be varied as desired, sixteen being shown in Fig. 1l. The plate 39 is provided with the guide pins 48 adapted to enter the guide sockets 49 in the upper plate 49, and the plate du is provided with similar pins 48 adapted to enter guide holes 59 in the die 45. In order to prevent air from being trapped in the cavities i6 and il as the walls of the envelope 23 are forced into these cavities, each cavity has a small Yvent hole 52 leading therefrom.

Since the envelope 23 is heated to a temperature of about 135 F. when placed in the mold of Fig. 8, the-se successive envelopes will supply heat to the mold plates 39 and 59' and gradually raise their temperature above that of the room f in which the press is being operated. It is desirable to maintain these mold platesV at room temperature or lower to cool the enveloper and stiifen the rubber somewhat before the mold is opened. This cooling of the plates 39 andv di] is secured by providing the plate 39 with the water cooling passages 53 and the plate il with Vthe water cooling passages 55s Since both of these mold plates move bodily during the operation of the press, the lower plate 39 has connected thereto the flexible inlet and outlet hose 55 and the upper plate lll! has connected thereto the flexible inlet and outlet hose 55. Y

The construction of the press'shown in Fig. 8 is such that when the envelope' 23 is placed between the mold plates 39 and l0 and` then the press is slowly closed by hydraulically raising the plunger lll, the` envelope with the liquid confined therein will be slowly squeezed between these plates. This will force the coni-ined liquid into the areas lying within the cavities l5 and M, and as the liquid passes from the other portions of the envelope into these mold cavities it will force the walls Il and I3 into these cavities to conform accurately to their contour. If the quantity of liquid confined in the envelope 23 has been accurately determined so that its volume is equal to the volume desired in one nished golf ball core multiplied by the number of cores to be formed from the envelope, which is sixteen in the present case, then by the time the press is closed all liquid should be pressed out from between the ilat walls of the envelope into these sixteen cavities, and each cavity should be completely filled with water as shown in Fig. 12, for example. l

At the time the envelope 23 is being pressed between the mold plates 39 and lll] the liquid may tend to escape around the marginal edges of the envelope. This however is prevented by providing the lower mold plate 39 with the slightly raised ri-b 5l positioned to surround the peripheral portion of the envelope and exert an added sealing pressure on the outer marginal edge of the envelope as will be apparent in Fig. 12. It is important to control accurately the space between the plates 39 and 40 during the final closing pressure so as not to flatten out the envelope more than is desired. This is accomplished by providing spacing shims in the form of strips 5S upon the plate 39. If it is desired to make liquid lled golf ball cores having walls that are .100"

thick, then thevulcanizable sheets Il and I3 should be calendered to a thickness of approximately .115", and if the sheets have this thi-ckness then the mold should be closed until the plates 39 and lll are spaced .185" apart. This will cause sufficient pressure to be exerted upon the flat portions of the sheets Il and i3 to bond them together rmly around the cavities.

When the parts of the press are in the position in which they are shown in Fig. 8 and the plunger 9| is raised it will'gradually exert an upward pressure upon the upper mold plate Il@ to force this plate upwardly into abutting contact with the lower face of the die 45, and it will be noted that the upper face of the plate 49 is cut away as at 59 to clear the downwardly extending cutting rings 69 provided upon the die 35. After the plate 40 has been forced against the die i5 further upward movement of the plunger M will serve to squeeze the side walls of the envelope 23 together and bond the at portions of the envelope walls Il and I3 firmly together as above mentioned. This bonding action will take place also within the cavities 46 and lll adjacent the vmeeting edges of these cavities as best shown in Fig. 12. 4

Since the water at W is highly non-compressible and thev unvulcanized rubber is also highly non-compressible, some excess rubber may spew out from the edges of the envelope 23 as the mold tioned, as the mold is forced to its maximum `closed position. This helps to control the amount 'of rubber in' a shell.

, After the sheetsv il .and flahave been firmly` xforced together asshown in Fig. 12 they will form vthe liquid filled shells S,and the press should be held closed for about thirty seconds vto prevent the stretched rubberfrom bouncing back to its former shape after the plunger 4i is lowered to open the press. As the plunger is lowered the envelope will pull free from one mold plate or the other, and it is preferred that it remain in Contact with the lower mold plate 39. The upper Y mold plate Ill] is then pushed rearwardly along the rails 44 to the position shown in Fig. 9 so that it will no longer lie between the plate 39 and die 45. The plunger 4| is then raised for a second time as shown in Fig. 9 so as to bring the envelope 23 in engagement with the cutting rings 60 of the die i and thereby cut the shells S out of the envelope in a manner best shown in Fig. 13. These cutting rings 6l] are'so constructed that they will pinch the rubber around the shell against the upper face of the plate 39 and thereby exert an added sealing pressure around the shell. This will produce a hashing ring 6l that should be later removed. The mold is then again opened so that the cut out shells S can be removed from the envelope, and each of these shells will have the appearance shown in Fig. 14.

The liquid filled shell of Fig. 14 can now be placed in a vulcanizing mold, not shown, provided with accurately formed semi-spherical mold cavities and this vulcanizing mold should be held tightly closed during the vulcanizing operation so that a vulcanizing temperature above the boiling point of water can be used without the internal pressure caused by the formation of steam within the shell prematurely opening the mold and therebyv allowing the shell to burst. The vulcanizing mold should be cooled well below the boiling point of water before the mold closing pressure is relieved and the mold opened. Fig. 15 shows a nished vulcanized golf ball core C from which the flashing 6I of Fig. 14 has been removed.

By employing the present method golf ball cores can be formed with walls of any desired thickness since this is controlled by the thickness of the calendered sheets Il and I3 used to form the envelope 23. The amount of liquid sealed in this envelope should be just enough to ll each shell accurately, as the present method utilizes this confined liquid to force the rubber stock into accurate conformation with the walls of the cavities and to nil each cavity. rlhe number of cavities provided in a mold may be varied extensively, but the greater the number of cavities used the greater will be the chances for some of the cavities to be under or over iilled with liquid. Good results have been secured by making sixteen shells at a time with the mold plate shown in Fig. ll. The water W introduced into the envelope 23 serves to dissolve the anti-tack lll and this improves the bond between the sheets/l l and l around the cavities, and particularly'inside the cavities where a strong bond is needed to keep the edges of the shell halves together with the water confined therein until these shells are vuleanized. The pressure exerted upon the noncavity portions of the envelope should be sufllcient to force all the conned water into the cavities and leave these faces almost dry.

It will be seen from the foregoing that by practicing the present method a number of liquid iilled golf ball cores all of the same size and weight can be easily produced.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. The method of making simultaneously a plurality of liquid iilled rubber cores which comprises, forming an envelope of` vulcanizable rubber having a wall thickness slightly greater than the wall thickness desired in the finished liquidfilled core, introducing therein an exact quantity of liquid equal to the total amount required in the nished liquid-filled cores and sealing the envelope so that it does not contain air, introducing this envelope into a press having a pair of mold plates in which are formed semi-spherical cavities disposed at the opposite sides of the envelope and adapted to cooperate to form spherical molds having the exact final volume desired for the core, Vpressing the envelope between said plates to force all of the liquid within the envelope into the cavity areas where it forces the envelope walls under hydraulic pressure into intimate engagement with the semi-spherical cavity walls and pressing the envelope walls together around the cavity confined liquid to form liquid-filled cores.

2..The method of making simultaneously a plurality of liquid filled rubber cores which comprises, forming an envelope of vulcanizable rubber having a wall thickness slightly greater than the wall thickness desired in the nished liquidilled core, introducing therein an exact quantity of liquid equal to the total amount required in the iinished liquid-lled cores and sealing the envelope so that it does not contain air, introducing this envelope into a press having a pair of mold plates in which are formed semispherical cavities disposed at the opposite sides of the envelope and adapted to cooperate to form spherical molds having the exact final volume desired for the core, pressing the envelope between said plates to force all of the liquid within the envelope into the cavity areas where it forces the envelope walls under hydraulic pressure into I- intimate engagement with the semi-spherical cavity walls and pressing the envelope walls together around the cavity conned liquid to form liquid-filled cores, and cutting these lled cores out of the envelope.

3. The method of making simultaneously a plurality of liquid lled rubber cores which comprises, forming an envelope of vulcanizable rubber having a wall thickness slightly greater than the wall thickness desired in the iinished liquidiilled core, introducing therein an exact quantity of liquid equal to the total amount required in the nished liquid-lled cores and sealing the envelope so that it does not contain air, introducing this envelope into a press having a pail.' of mold plates in which are formed semi-spherical cups disposed at the opposite sides of the envelope and adapted to cooperate to form spherical molds having the exact final volume desired for the core, pressing the envelope between said plates to force all of the liquid within the envelope into these cups where it forces the envelope walls under hydraulic pressure into intimate engagement with the walls of said cups and pressing the envelope wall together around the cups without causing the cup edges to meet to form liquid-lled cores, and cutting these filled cores out of the envelope.

4. The method of making liquid-lilled golf ball cores which comprises, forming an envelope of vulcanizable rubber having a wall thickness slightly greater than the wall thickness desired in the finished liquid-nlled core, introducing therein an exact quantity of liquid equal to the total amount required in the finished liquid-lled cores and sealing the envelope so that it does not contain air, introducing this envelope into a press having a pair of mold plates in which are formed semi-spherical cups disposed at the opposite sides of the envelope and adapted to cooperate to form spherical molds having the exact nal EDWIN C. UHLIG.

1 l REFERENCES CITED The following references are of record in the le of this patent:

I, UNITED STATES PATENTS Number Name Date Paine May 27, 1902 Hopkins Sept. 8, 1925 Riel Sept. 12, 1939 Kalowsky June 15, 1943 

